-LRB- CNN -RRB- -- The on-going reports about child molestation in the Catholic church have led the public and the media to ask what causes someone to be sexually attracted to children . Scientists use the word pedophilia to refer to the sexual preference for children before puberty -LRB- usually , before age 11 -RRB- , and the word hebephilia , to refer to the sexual preference for children at puberty -LRB- usually , ages 11 to 14 -RRB- .

Although there have been claims that child molestation is a result of homosexuality -LRB- or of celibacy -RRB- , there is absolutely no basis in science for either conclusion . The scientific evidence instead suggests that pedophilia and hebephilia are caused by atypical brain development occurring near or before birth .

MRI research has found very large differences in brain structure between men who have a sexual preference for children and those who have a sexual preference for adults . These differences were detected as regions of low density in brain tissue called white matter . White matter is what connects the various parts of the brain , enabling it to function as a whole . The white matter that is affected in pedophilia and hebephilia is the white matter that connects the parts of the brain that respond to sexual images . -LRB- Specifically , these regions were the superior occipitofrontal fasciculus and the arcuate fasciculus . -RRB-

There does not exist any evidence that gay men share this feature of decreased white matter . In fact , there is some evidence that gay men have areas of more white matter than straight men , in at least some parts of the brain -LRB- called the corpus callosum -RRB- .

Also demonstrating that gay men have no more of a sexual interest in children than do straight men are studies that have measured sexual responses directly : There exists a test , called a phallometric test , in which a man is shown images of adults and children , both male and female , while he wears a device on his penis to detect even very small changes in blood volume . The procedure is routinely used with sexual offenders , and research has repeatedly shown phallometric testing to be one of the most -- if not the single most -- accurate predictor of who is the most likely to commit future sexual offenses . When regular gay men and regular straight men -LRB- not offenders -RRB- are tested , gay men respond to images of children in exactly the same way that straight men do : very little .

Out of typical men , approximately two to three percent have a sexual preference for men rather than women , and out of pedophilic/hebephilic men , approximately 20 to 30 percent have a sexual preference for boys rather than girls . It is an error , however , to conclude from this that the two to three percent who prefer men are more likely than the others to break out of their preferences to contact a child sexually . That is , the offenses against boys are being committed by the 20 to 30 percent of pedophiles who prefer boys , not by the two to three percent of otherwise typical men who prefer men .

The misconception that gay men pose a disproportionate risk to children comes from a misunderstanding of men 's sexual preferences : Pedophilia is the genuine sexual preference for children . The evidence suggests that these are innate and immutable characteristics . Pedophilia/hebephilia is not a temporary state from which those who prefer boys can become typical gay men , nor from which those who prefer girls can become typical straight men . Nor is there any known route by which someone with a genuine sexual preference for adults can develop a genuine sexual preference for children , either girls or boys .

Although it is reasonable to question why the Catholic priesthood appears to include so many pedophilic or hebephilic men , there is no scientific evidence that homosexuality is the answer , nor that fostering discrimination against gay men could be a solution .

The opinions expressed in this commentary are solely those of Dr. James Cantor . Click here more information and updates on his research .

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There is no scientific evidence to link gay men and child molesters

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MRI research shows distinct differences in brain structure between the two

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Pedophilia/hebephilia is not a temporary state from which one can become a typical gay man